Abstract: In a flat-type discharge lamp composed of a first dielectric plate integrally formed at its inner surface with a plurality of spaced dielectric ribs at the same height defined by a specified discharge distance, a second dielectric plate assembled in parallel with the first dielectric plate to form a sealed space to be filled with inert gas, and electrodes in the form of a thin membrane respectively deposited on the outer surfaces of the dielectric plates, wherein the electrodes are applied with a specified voltage to cause discharge in inert gas filled in spaces among the dielectric ribs within the sealed space thereby to produce visible light on a light emitting surface formed on at least one of the electrodes, the first dielectric plate is formed at its outer peripheral edge with an outer peripheral frame having a support surface of the same height as the dielectric ribs, the second dielectric plate being bonded by an adhesive coated in a recess formed along one side of the support surface and secured tight